In the field of medical practice, there is known to be frequent need for sponging the body to remove therefrom body fluids such as blood, serum, plasma, lymph, spinal fluid, tissue fluid, urine, sweat, bile juice, digestive juice etc. That is to say, during a surgical incision it is necessary to sponge the areas approximate to the incision to remove blood and other fluids emanating therefrom. After entering the operative field, it is also customary to use sponges to isolate various organs from the field by packing them with the sponges to prevent them from interfering with the operation. Sponges of varying size and configuration are also utilized in such areas of surgery as ophthalmic surgery, neurosurgery, spinal surgery and the like for the same purpose.
Hydrophilic sponges prepared from polyurethane foams are well known in the art. For example, such a sponge is disclosed in U.S. Pat. No. 3,566,871. Similarly, compressed polyurethane foams have been disclosed as useful bandage components in U.S. Pat. No. 3,665,918. Additionally, U.S. Pat. Nos. 3,098,048; 3,149,000; 3,326,823 and 3,463,745 also specify various hydrophilic polyurethane foams and how they may be modified so as to render them useful for various applications, usually in the medical field.
While these foam products of the prior art are useful in many applications, they suffer from at least two main deficiencies which render them less attractive for other uses. The prime deficiency of these prior art materials resides in the tendency of the foam from which they are prepared to retain its elastic memory over the life of the material. As a result, the tendency of the material to "bounce back" into its original shape after having been folded, crumpled etc. destroys its usefulness where retention of shape is desired, if not necessary. This so called "drape" or "dead fold" of the foam is insufficient if some maximum degree of shape retention cannot be attained.
A second detrimental property of the known prior art polyurethane foams is their unsatisfactory "hand" i.e. the roughness or abrasive quality of their outer surface due to the exposed cells of the foam. In areas of use where a very limp hand is required in order not to aggravate the body part with which the material comes in contact, these prior art foams are unattractive and, in fact, useless.